Model

<!ENTITY % book-app-group-model
                        "(book-part-meta?,
                          (%para-level;)*, (%sec-level;)*,
                          (book-app)+ )"                             >

Expanded Model

(book-part-meta?, (address | alternatives | answer | answer-set | array | boxed-text | chem-struct-wrap | code | explanation | fig | fig-group | graphic | media | name-address-wrap | preformat | question | question-wrap | question-wrap-group | supplementary-material | table-wrap | table-wrap-group | disp-formula | disp-formula-group | def-list | list | tex-math | mml:math | p | related-article | related-object | ack | disp-quote | speech | statement | verse-group | x)*, (sec)*, (book-app)+ )